1. Field of the Invention
The present invention relates to a roller member urging mechanism and an image forming apparatus provided with the same.
2. Description of the Related Art
In a conventional image forming apparatus such as a color printer, an urging mechanism pushes a transferring roller arranged under a transferring belt upward so as to allow the transferring roller come in press contact with the transferring belt, so that a transferring processing is performed assuredly when an image is transferred from a photoconductive drum to the transferring belt, or from the transferring belt to a recording sheet.
FIGS. 8 and 9 show a conventional urging mechanism for a transferring roller. This transferring roller 116 (refer to FIG. 9) is retained on a casing 109 being electrically insulative. The casing 109 is provided with a bearing 108 being electrically conductive for receiving a roller shaft 116b of the transferring roller 116, and a strip member 110 which serves as a contact to an unillustrated other unit to supply electricity to the transferring roller 116 through the bearing 108. A coil spring 111 is arranged between the strip member 110 and the bearing 108. The coil spring 111 pushes up the transferring roller 116 along with the bearing 108 to allow the transferring roller 116 to come in press contact with a transferring belt and the like.
Further, in Japanese Patent Unexamined Publication No. 2000-250333, there is disclosed an urging mechanism having a strip member formed with a projecting portion on its upper surface and a coil spring arranged between the projecting portion and a bearing in a compressed state. In this urging mechanism, the transferring roller axially supported on the bearing member is supplied with electricity and pushed up.
However, since a coil spring and a strip member are used for supplying electricity to a transferring roller and pushing up the transferring roller in the conventional urging mechanisms, it is difficult to reduce the number of parts. Further, since there are provided many parts constituting a passage for supplying electricity to the transferring roller, malfunction in electric current is likely to occur.